May 9 (Reuters) - Australia's Westpac Banking Corp on Monday posted over a 12% drop in first-half cash earnings, as its margins continued to be squeezed by stiff competition in mortgage lending amid record low interest rates.

The country's third-largest bank said cash earnings were A$3.10 billion ($2.19 billion) for the six months ended March 31, compared with A$3.54 billion reported last year and a Visible Alpha consensus of A$2.83 billion. ($1 = 1.4154 Australian dollars) (Reporting by Savyata Mishra in Bengaluru; Editing by Leslie Adler)